The present invention relates generally to holding devices for use in connection with motorcycles, and in particular to a holding device for supporting saddlebags, baggage pieces, blinkers, reflectors, and the like. A holding device of this kind, which is produced by pressure casting, is described and illustrated in the German Gebrauchsmuster 7 707 615. This known holding device includes a right-side and a left-side lateral holding member for supporting saddlebags or baggage pouches, two upper frames mounted on the lateral holding members, a transverse baggage rack secured to the upper frames and interconnecting the latter, and an adjustable transverse strutting attached to the lateral holding members. In this known embodiment of a holding device, the baggage rack between the upper frames is rigidly connected to the latter. When this prior-art holding device is installed on a motorcycle having an upwardly swingable seat, as is the case in most types of motorcycles, such prior-art holding device frequently either totally prevents the seat from being swung up or in any case permits only partial lifting of the seat. It is necessary, however, that the seat be readily swingable, inasmuch as tool accessories and in many cases the battery is located therebeneath, and an easy and unobstructed access to these parts must always be preserved. It is a serious drawback of the prior-art holding device that, in order to open up the compartment below the seat, it is necessary to dismantle the baggage rack between the lateral holding parts, which operation is inconvenient, tiresome and time-consuming. As soon as a tool and/or the battery and other parts, such as gloves or the like are again replaced under the seat and the latter is swung down, the baggage rack must again be screwed to the frame parts of the holding device, and this operation is equally troublesome as the dismantling of the rack.